After the Spanish garrisons had evacuated the posts they occupied at the Natchez and Walnut Hills the commissioner of the United States commences his observations to ascertain the point near the Mississippi which terminated the northernmost part of the 31st degree of north latitude. From thence he proceeded to run the boundary line between the United States and Spain. He was afterwards joined by the Spanish commissioner, when the work of the former was confirmed, and they proceeded together to the demarcation of the line. Recent information renders it probable that the Southern Indians, either instigated to oppose the demarcation or jealous of the consequences of suffering white people to run a line over lands to which the Indian title had not been extinguished, have ere this time stopped the progress of the commissioners; and considering the mischiefs which may result from continuing the demarcation in opposition to the will of the Indian tribes, the great expense attending it, and that the boundaries which the commissioners have actually established probably extend at least as far as the Indian title has been extinguished, it will perhaps become expedient and necessary to suspend further proceedings by recalling our commissioner. The commissioners appointed in pursuance of the 5th article of the treaty of amity, commerce, and navigation between the United States and His Britannic Majesty to determine what river was truly intended under the name of the river St. Croix mentioned in the treaty of peace, and forming a part of the boundary therein described, have finally decided that question. On the 25th of October they made their declaration that a river called Scoodiac, which falls into Passamaquoddy Bay at its northwestern quarter, was the true St. Croix intended in the treaty of peace, as far as its great fork, where one of its streams comes from the westward and the other from the northward, and that the latter stream is the continuation of the St. Croix to its source. This decision, it is understood, will preclude all contention among the individual claimants, as it seems that the Scoodiac and its northern branch bound the grants of land which have been made by the respective adjoining Governments. A subordinate question, however, it has been suggested, still remains to be determined. Between the mouth of the St. Croix as now settled and what is usually called the Bay of Fundy lie a number of valuable islands. The commissioners have not continued the boundary line through any channel of these islands, and unless the bay of Passamaquoddy be a part of the Bay of Fundy this further adjustment of boundary will be necessary, but it is apprehended that this will not be a matter of any difficulty.